Impact of Spacings on Sapwood and Heartwood Thickness in Picea Mariana (Mill.) B.S.P. and Picea Glauca (Moench.) Voss

K. C. Yang, G. Hazenberg


The impact of spacing on sapwood and heartwood thickness was studied in a 38-year-old plantation in northern Ontario. Ten trees each of Picea mariana (Mill.) B.S.P. and Picea glauca (Moench.) Voss grown at spacings 1.8 m x 1.8 m, 2.7 m x 2.7 m, and 3.6 m x 3.6 m were randomly selected for the study. Tree diameter, sapwood and heartwood thickness, both as a ring count and as a length measure, and sapwood and heartwood basal area were measured. For both species, it was found that the effect of the 1.8-m x 1.8-m spacing usually was significantly different from that of the other two levels. Only for sapwood basal area in Picea mariana were all three levels of spacing declared statistically significant from each other. Sapwood basal area increased with increased spacing for this species. For Picea glauca, the maximum sapwood basal area occurred at the second level of spacing. Sapwood basal area occupied approximately half of the total tree basal area at age 38. The number of sapwood rings in Picea glauca showed no significant differences over the levels of spacing. It is concluded that spacing plays an important role and has various degrees of impact on tree diameter and heartwood and sapwood thickness.


Spacing;sapwood thickness;heartwood thickness;Picea mariana;Picea glauca

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